How does SLA work?

[JMK]

I know the basics. A liquid polymer resin is hardened by a laser or light beam. However, I don't understand how the laser can only hit the surface and harden 0.001mm of that surface, without penetrating deeper into the liquid. How is this possible?

Also, is the laser a single point, whereas it only cures the resin one tiny dot at a time, or is it curing it an entire layer at a time?

I'm just wondering this stuff. Maybe I sound stupid, but I need to know, because its been bugging me

[MeoWorks]

I don't quite understand it myself, I've scanned through some diys so your answer might be there

[pathfindr]

JMK, I am no expert but I believe it is a single point. The light cures it in more of a point by point method rather than layer at a time. Although there is a 3D printer coming out that claims to do entire layers at a time (I forget the name). I don't know how it hits only 0.001mm of the surface either. Sometimes it isn't even a laser, and in steam UV light.

[Geoff]

http://lmgtfy.com/?q=how+do+dlp+printers+work

[kanningphish]

Thanks for sharing Geoff. I've heard a lot of people talk negatively about SLA but in all honesty, I think it will make FFF printing a thing of the past within a couple years.

[Feign]

Both SLA and FFF have their pros and cons. Neither one is going to make the other obsolete in the consumer market.

PolyJet will eventually make both of them obsolete... But it will still be locked behind overlapping patents for a long time.

[3DPBuser]

The work that I do can only use FFF because the parts are for products that must be strong and waterproof.

[Dragons_Blood]

Isn't SLA printed objects stronger? At least that's what I would assume. Are they not waterproof either?